Fetal blood sampling is extensively employed during births where the doctor suspects that the infant may be receiving an improper supply of oxygen due, for example, to strangulation by the umbilical cord or premature separation of the placenta. Conventionally, such sampling involves passing an endoscope through the birth canal and pressing it onto the fetal presentation. The field is swabbed as dry as possible with long swab holders projecting through the endoscope, and a jelly is similarly applied to induce a large drop of blood to form. The doctor then introduces a lance through the endoscope to make an incision. After the incision is made, the lance is removed and a long glass capillary tube is advanced to collect a sample of the blood.
This technique is associated with difficulty since fetal movement often occurs to change the field and contamination of the drop of blood is possible which results in errors in pH readings. In practice, the movement of the fetal part and the fact that the procedure is carried out at a distant vision causes some difficulty in easily obtaining a sample and, even then, the results so obtained may not be completely reliable. Moreover, this technique is relatively time consuming and clumsy in that a plurality of different parts must be inserted and removed in a series of separate steps.
One attempt to avoid the problems noted above is disclosed in U.S. Pat. No. 3,685,509 to Bentall which discloses a fetal blood sampling endoscope having an evacuated tubular end portion for adhering to the body part. A non-removable custom-formed capillary tube is threaded through the walls of the device until one end of the tube is flush with the part engaging the end of the endoscope. A lance freely movable in the endoscope is manually advanced to puncture the skin, with the capillary tube disclosed as being capable of collecting blood issuing therefrom. The disclosed technique has several drawbacks. This concept introduces a new requirement for additional equipment in that suction must be applied to annulus of the endoscope. The necessity for additional equipment is both costly and burdensome. The hand-held lance which is freely moveable in the device must be manually aimed by the doctor and guided onto a target point on the body in order to make a properly located incision which may be collected by the capillary tube. The doctor may encounter some difficulty in accomplishing this feat. It has been discovered that skin adjacent the puncture may cover the end of the capillary tube when the tube is flush with a squared off end surface such as shown in this reference. Finally, the capillary tube of the reference is not removable thereby requiring a relatively large quantity of blood to be collected or necessitating the use of external suction to obtain the blood from the opposite tube end.
The present invention is directed to solving one or more of the problems set forth above.